Reservoir Distribution Of The Triassic Baikouquan Formation In Moxizhuang-Yongjin Area

At present,there is great potential of oil&gas exploration and development in the Mahu sag.By studying the distribution of reservoirs in the corresponding blocks,we are going to provide some effective suggestions for the further exploration and development.Based on the full use of seismic,logging,and basic geological data of Moxizhuang-Yongjin area,the research was carried out from the aspects of stratigraphic sequence correlation,fine structure interpretation,sedimentary system study and reservoir evaluation.There is a three-order sequence of Triassic Baikouquan formation in study area.The interior can be divided into three fourth-order sequences,corresponding to the first,second and third sections of Baikouquan Formation.Through the study of stratigraphic contrast profiles including east-west and north-south direction in Mahu sag,the formation and sand are getting thicker.The first and second sections of Bai Kou Quan mainly distributed in the northwest area.and the sand body get thiner with the direction changed from west-north to east-south,the third section only contains a little sand in the north of study area.At the same time,the fine structure interpretation work shows that the faults have different characters in different study area.There are few faults in north and south part which are normal faults with the northwest-west direction,and the fault displacement is between 5m to 50m.The central part contains a number of fault combinations which are parallel to each other,four of these faults extender longer than others in this part.According to the sedimentary system study and reservoir evaluation,the bottom deposition of Bai Kou Quan formation belongs to fan delta plain while the top belongs to fan delta front.We get only one penetration well SHA12 in study area.The reservoir was found between 5124.80m to 5392.50m in well SHA12 with the sandy conglomerate.The permeability and porosity of this reservoir is poor with the average log porosity of 1.5%,and the average log permeability 8.18×10^-3?m².Some area even gets poorer reservoir performance.According to the above research results and the characteristics of seismic data of Baikouquan formation,it is believed that the reservoir is mainly distributed in the north-west part of the study area.The thickness is reducing as the direction getting closer to east-south.From the wave impedance inversion plan and the sand body thickness plan of the Baikouquan formation,the sand bodies in the northwestern part of the study area are concentrated,getting thinner from northwest to southeast.The maximum thickness of the sand body is about 130m,and the thinner area is 40-50m.The sand bodies on the section are mainly distributed in the middle and lower parts of the Baikouquan formation.